Academic literature on the topic 'Long-term field experiments'
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Journal articles on the topic "Long-term field experiments":
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Merbach, W., and A. Deubel. "Long-term field experiments – museum relics or scientific challenge?" Plant, Soil and Environment 54, No. 5 (May 19, 2008): 219–26. http://dx.doi.org/10.17221/395-pse.
Abstract:
By reference to the Eternal Rye trial in Halle, Germany, as an example, it is demonstrated that long-term trials provide indispensable information for contemporary and future land use research. These trials serve as tools for the examination of cultivation measures or the effects of climate on nutrient dynamics and mobilization, microbial biodiversity, mineral composition or soil formation processes. They are therefore essential for the evaluation of land-use strategies or climatic change and, because of that, can provide more accuracy in related political considerations.
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Frye, W. W., and G. W. Thomas. "Management of Long‐Term Field Experiments." Agronomy Journal 83, no. 1 (January 1991): 38–44. http://dx.doi.org/10.2134/agronj1991.00021962008300010012x.
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Brown, J. R. "Summary: Long‐Term Field Experiments Symposium." Agronomy Journal 83, no. 1 (January 1991): 85. http://dx.doi.org/10.2134/agronj1991.00021962008300010020x.
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Christensen, Bent T. "The Askov long‐term field experiments." Archives of Agronomy and Soil Science 42, no. 3-4 (December 1997): 265–78. http://dx.doi.org/10.1080/03650349709385732.
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Balík, Jiří, Jindřich Černý, Martin Kulhánek, and Ondřej Sedlář. "Soil carbon transformation in long-term field experiments with different fertilization treatments." Plant, Soil and Environment 64, No. 12 (November 30, 2018): 578–86. http://dx.doi.org/10.17221/591/2018-pse.
Abstract:
Soil carbon transformation was observed in long-term stationary field experiments (longer than 20 years) at two sites with different soil-climatic conditions (Luvisol, Chernozem). The following crops were rotated within the trial: row crops (potatoes or maize)-winter wheat-spring barley. All three crops were grown each year. Four different fertilization treatments were used: (a) no fertilizer (control); (b) sewage sludge (9.383 t dry matter/ha/3 years); (c) farmyard manure (15.818 t dry matter/ha/3 years); (d) mineral NPK fertilization (330 kg N, 90 kg P, 300 kg K/ha/3 years). At the Luvisol site, the control treatment showed a tendency to decrease organic carbon (C<sub>org</sub>) in topsoil. At organic fertilization treatments the content of C<sub>org</sub> increased: sewage sludge – +15.0% (Luvisol) and +21.8% (Chernozem), farmyard manure – +19.0% (Luvisol) and +15.9% (Chernozem). At the NPK fertilization, the increase was +4.8% (Luvisol) and +4.7% (Chernozem). The increased C<sub>org</sub> content was also associated with an increase of microbial biomass carbon (C<sub>mic</sub>) and extractable organic carbon (0.01 mol/L CaCl<sub>2</sub> and hot water extraction). The ratio of C<sub>mic</sub> in C<sub>org</sub> was within the range 0.93–1.37%.
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Vašák, F., J. Černý, Š. Buráňová, M. Kulhánek, and J. Balík. "Soil pH changes in long-term field experiments with different fertilizing systems." Soil and Water Research 10, No. 1 (June 2, 2016): 19–23. http://dx.doi.org/10.17221/7/2014-swr.
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Černý, J., J. Balík, M. Kulhánek, and V. Nedvěd. "The changes in microbial biomass C and N in long-term field experiments." Plant, Soil and Environment 54, No. 5 (May 19, 2008): 212–18. http://dx.doi.org/10.17221/393-pse.
Abstract:
Microbial biomass nitrogen and carbon were studied in long-term field experiments with continuous cultivation of silage maize and with crop rotation. A positive effect of organic fertilizers on the microbial biomass nitrogen and the carbon content in soil was observed. Statistically significant effect of organic fertilizers on the higher content of microbial biomass C and N was established in the first year after their application. During the application the content of microbial biomass carbon and nitrogen decreased, but there were higher biomass C and N contents compared to control, even without statistical significance. A negative effect on microbial biomass carbon and nitrogen content in soil came from the application of mineral nitrogen fertilizers in experiments with maize. Statistically significant effect of mineral N fertilizers was observed after their application. In the course of the N fertilizers application the content of microbial biomass carbon and nitrogen was lower than control. No statistically significant effects of mineral nitrogen fertilizers on the microbial biomass nitrogen and carbon content were observed in field experiments with crop rotation over the eight years of experiment duration. The higher effect of mineral and organic fertilizers application on the changes in microbial biomass C and N was reported in experiments with continuous cultivation of maize compared to experiments with crop rotation.
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Peterson, G. A., D. J. Lyon, and C. R. Fenster. "Valuing Long-Term Field Experiments: Quantifying the Scientific Contribution of a Long-Term Tillage Experiment." Soil Science Society of America Journal 76, no. 3 (May 2012): 757–65. http://dx.doi.org/10.2136/sssaj2011.0413.
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Balík, Jiří, Jindřich Černý, Martin Kulhánek, Ondřej Sedlář, and Pavel Suran. "Balance of potassium in two long-term field experiments with different fertilization treatments." Plant, Soil and Environment 65, No. 5 (May 27, 2019): 225–32. http://dx.doi.org/10.17221/109/2019-pse.
Abstract:
Balance of potassium (K) was observed in long-term stationary field experiments (21 years) at two sites with different soil and climatic conditions (Luvisol, Cambisol). The following crops were rotated within the trial: potatoes- winter wheat-spring barley. All three crops were grown each year. The trial comprised 6 treatments: (1) no fertilization; (2) farmyard manure; (3) half dose of farmyard manure + nitrogen (N) in mineral nitrogen fertilizers; (4) mineral nitrogen fertilizers; (5) NPK in mineral fertilizers; (6) straw of spring barley + N in mineral nitrogen fertilizers. The recovery rate of potassium from farmyard manure by crops was 24–26%, from mineral fertilizers it was 27–52%. Different fertilization intensities were manifested by significant differences in the content of exchangeable K in soil. Changes in non-exchangeable K (K<sub>ne</sub>) were recorded only at the Luvisol site (850 mg K<sub>ne</sub>/kg), but not at the Cambisol site (3000 mg K<sub>ne</sub>/kg). The maximum negative balance (–2376 kg K/ha/21 years) was recorded at the mineral nitrogen fertilization treatment.
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Sibbesen, Erik. "Soil movement in long-term field experiments." Plant and Soil 91, no. 1 (February 1986): 73–85. http://dx.doi.org/10.1007/bf02181820.
Dissertations / Theses on the topic "Long-term field experiments":
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Walters, Evan Robert. "Sulfate Reducing Bioreactor Dependence on Organic Substrates for Long-Term Remediation of Acid Mine Drainage." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1397.
Abstract:
Coal-generated acid mine drainage (AMD) is characterized by low-pH waters with excessive loads of dissolved species such as SO4, Fe, Al and Mn along with other elements of environmental concern (i.e. Cd, As, Cr, Ni, Pb, Se and Cu). To mitigate this problem, anaerobic sulfate reducing bioreactors (ASRB) have been implemented as a technology for passive treatment systems that utilize low-cost organic substrates to stimulate biologically enhanced contaminant sequestration. Previous work has identified the establishment of diverse microbial communities in which a hierarchal chain of substrate degradation processes is essential in developing sustainable environments to produce long-lived sulfate-reducing microbial (SRM) populations. In this study, to determine the optimal mixture of substrate types, alternating ratios of herbaceous (ie. leaves, grass, spent brewing grains) and ligneous (i.e. maple wood chips and saw dust) reactor matrices were tested. Five bioreactors along with one control reactor containing only limestone were constructed at the Tab-Simco abandoned mine land (AML) site in southern Illinois, USA. The field experiments were monitored over ~ one year (377 days) to evaluate the physical, geochemical and microbiological parameters which dictate ASRB efficiency in remediation of AMD contaminants. Results from this experiment documented contaminant removal in all reactors. However, the bioreactors established SRM populations that contributed to enhanced removal of SO4, Fe, and trace metals (i.e. Cu, Cd, Zn, Ni). Geochemical assessment of the aqueous environments established within the bioreactors suggested multiple pathways of contaminant sequestration. This included the formation of Fe-oxyhydroxide precipitates, adsorption, co-precipitation (e.g. Zn/Ni-Ferrites) and bio-induced sulfide mineralization. Activity of the SRMs was dependent on temperature, with bioreactors exhibiting decreases in both effluent sulfide concentrations and 34S-depletion of sulfate during low-T months (i.e. T < 10°C). Overall, maximum remediation of dissolved constituents SO4, Fe, Al and Mn was obtained in the predominantly herbaceous bioreactors. Extrapolation of our results to the full-scale Tab-Simco bioreactor indicated that, over the course of one year, the herbaceous bioreactors would remove ~75,600 kg SO4, 21,800 kg Fe, 8000 kg Al, and 77 kg Mn. This represents a 21.7 wt%, 41.5 wt%, 9.4 wt% and 81.8 wt% increase in SO4, Fe, Al and Mn removal over dominantly ligneous bioreactors, respectively. Although the overall Fe removal within the limestone control reactor reached 44.5 mol%; removal of 19.5 mol% SO4 and 36.9 mol% Al from influent AMD were significantly less when compared to the bioreactors. These results imply that ASRB technologies are promising in remediation of coal-generated AMD and increasing herbaceous content of bioreactors can significantly enhance contaminant sequestration. However, geochemical results also displayed seasonal variation in redox gradients within our field ASRB's which may induce dissolution of the redox sensitive phases produced within bioreactors. Furthermore, optimal microbial-mediated sulfate reduction may be inhibited by the high surface areas of the abundant Fe/Al-oxyhydroxides which dominate the system. Therefore, to enhance ASRB remediation capacity, future designs must optimize not only the organic carbon substrate but also include a pretreatment phase in which the bulk of dissolved Fe/Al-species are removed from the influent AMD prior to entering the bioreactor.
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Bergkvist, Petra. "Long-term fate of sewage-sludge derived cadmium in arable soils : laboratory and field experiments, and modelling with SLAM and WHAM /." Uppsala : Dept. of Soil Sciences, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a410.pdf.
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Lång, Elisabeth. "Short- and Long-Term Influences of Education, Health Indicators, and Crime on Labor Market Outcomes : Five Essays in Empirical Labor Economics." Doctoral thesis, Linköpings universitet, Nationalekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-140649.
Abstract:
The objective of this thesis is to improve the understanding of how several individual characteristics, namely education (years of schooling), health indicators (height, weight, smoking, alcohol consumption, and exercise), criminal behavior, and crime victimization, influence labor market outcomes in the short and long run. The first part of the thesis consists of three studies in which I adopt a within-twin-pair difference approach to analyze how education, health indicators, and earnings are associated with each other over the life cycle. The second part of the thesis includes two studies in which I use field experiments in order to test the employability of exoffenders and crime victims. The first essay, Learning for life?, describes an analysis of the education premium in earnings and health-related behaviors throughout adulthood among twins. The results show that the education premium in earnings, net of genetic inheritance, is rather small over the life cycle but increases with the level of education. The results also show that the education premium in health-related behaviors is mainly concentrated on smoking habits. The influences of education on earnings and health-related behaviors seem to work independently of each other, and there are no signs that health-related behaviors influence the education premium in earnings or vice versa. The second essay, Blowing up money?, details an analysis of the association between smoking and earnings in two different historical social contexts in Sweden: the 1970s and the 2000s. I also consider possible differences in this association in the short and long run as well as between the sexes. The results show that the earnings penalty for smoking is much stronger in the 2000s as compared to the 1970s (for both sexes) and that it is larger in the long run as compared to the short run (for men). The third essay, Two by two, inch by inch, describes an analysis of the height premium among Swedish twins. The results show that the height premium is relatively constant over the life cycle and that it is larger below median height for men and above median height for young women. The estimates are similar for monozygotic and dizygotic twins, indicating that environmentally and genetically induced height differences are similarly associated with earnings over the life cycle. The fourth essay, The employability of ex-offenders, published in IZA Journal of Labor Policy (2017), 6:6, details an analysis of whether male and female exoffenders are discriminated against when applying for jobs in the Swedish labor market. The results show that employers do discriminate against exoffenders but that the degree of discrimination varies across occupations. Discrimination against ex-offenders is pronounced in female-dominated and high-skilled occupations. The magnitude of discrimination against exoffenders does not vary by applicants’ sex. The fifth essay, Victimized twice?, describes an analysis of whether male and female crime victims are discriminated against when applying for jobs in the Swedish labor market. This study is the first to consider potential hiring discrimination against crime victims. The results show that employers do discriminate against crime victims. The discrimination varies with the sex of the crime victim and occupational characteristics and is concentrated among high-skilled jobs for female crime victims and among femaledominated jobs for male crime victims.
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Ravelojaona, Nomena. "Evaluation of STICS model performance for long-term simulation of biomass production and nitrogen nutrition of spring barley and timothy cultivated in two important agricultural regions in Quebec (Canada)." Electronic Thesis or Diss., Bordeaux, 2023. http://www.theses.fr/2023BORD0503.
Abstract:
L’orge de printemps (Hordeum vulgare L.) et la fléole des prés (Phleum pratense L.) sont des cultures de première importance économique pour la Province du Québec et d’autres régions de climat continental froid et humide (Amérique du Nord, les pays nordiques…). Les modèles sol-culture sont des outils puissants capables de calculer de nombreuses variables d’intérêt agronomique et environnemental. Ils sont conçus pour simuler les interactions complexes entre les cultures, l'eau et l'azote (N) du sol dans le continuum sol–plante–atmosphère. Entre autres modèles, STICS est un modèle sol–culture basé sur les processus, qui a été développé initialement pour des conditions agropédoclimatiques de régions tempérées. Cependant, étant un modèle générique, il est possible de l’adapter aux conditions d’autres agrosystèmes.Les objectifs de cette thèse étaient d’analyser et d’élargir le domaine d’application de STICS à ces deux cultures d’importance économique cultivées dans des conditions agropédoclimatiques de la province de Québec et d’évaluer les performances prédictives du modèle sur des simulations sur le long terme. Cette thèse est une contribution à l’étude de la généricité de STICS pour des agrosystèmes québécois. Outre le contexte climatique, l’originalité de ce travail porte sur les cultures étudiées, orge de printemps et fléole des prés, et le nombre d’années successives de simulations en continu (sans réinitialisation annuelle). Les performances prédictives de STICS ont été analysées pour la production de biomasse aérienne annuelle, sa teneur en N et la quantité de N exporté pour i) une monoculture d’orge de printemps de 31 ans cultivée avec deux modes de travail du sol et fertilisée avec deux sources de N différentes (engrais azoté minéral et lisier de vaches laitières) ; et ii) une prairie de fléole des prés de 8 ans, fertilisée chaque année avec quatre doses d’engrais azoté minéral (0, 60, 120, 180 kg N ha-1). Nous avons utilisé les bases de données de deux dispositifs expérimentaux au champ d’Agriculture et Agroalimentaire Canada.Pour la monoculture d’orge, la procédure de calibration de STICS a nécessité l'ajustement des paramètres de cultivar en particulier, confirmant ainsi la généricité de la plupart des paramètres des plantes définis dans STICS. Les valeurs simulées sur une période de 31 ans se sont révélées être correctement en accord avec les valeurs observées des variables d’intérêt pour les différents traitements, mais avec une plus grande dispersion pour la nutrition azotée. Les résultats de la simulation des attributs de la production végétale au moment de la récolte étaient plus précis pour les années où les précipitations étaient proches de la normale. Pour la prairie de fléole des prés suivie pendant 8 ans, la correspondance entre les valeurs observées et simulées était satisfaisante pour la première coupe effectuée au printemps. STICS a correctement simulé l'effet positif de la dose de fertilisation azotée sur la production de biomasse et la nutrition azotée des plantes. Néanmoins, les valeurs simulées étaient surestimées par le modèle en l’absence de fertilisation azotée. Si l’on excepte cette situation très particulière, non représentative des pratiques agronomiques, les performances de STICS sont donc satisfaisantes dans le contexte dans le contexte des deux essais au champ étudiés. De plus, STICS a bien reproduit la tendance à la baisse de la productivité de la fléole des prés observée en fonction de l'âge de la prairie. Les résultats ont montré que cette baisse de rendement au fil du temps est fortement corrélée à la réduction de la réserve métabolique dans les organes de réserve.En conclusion, ce travail de thèse a montré l’applicabilité et la fiabilité du modèle STICS pour la simulation sur le long terme de la production de biomasse et de la nutrition azotée d'orge de printemps et de la fléole des prés dans des conditions agropédoclimatiques de la Province de QuébecSpring barley (Hordeum vulgare L.) and timothy (Phleum pratense L.) are crops of prime economic importance for the province of Quebec and other regions with cold, humid continental climate (North America, Nordic countries, etc.). Soil-crop models are powerful tools for calculating, a wide range of agronomic and environmental variables, since they are designed to simulate the complex interactions between crops, water, and soil nitrogen (N) in the soil–plant–atmosphere continuum. Among other models, STICS is a process-based soil-crop model developed initially for temperate agropedoclimatic conditions. However, it can be adapted to conditions of other agrosystems.The objectives of this thesis were to analyze and extend the scope of application of STICS to these two economically important crops grown under agropedoclimatic conditions in the Province of Quebec, and to evaluate the model's predictive performance on long–term simulations. This thesis is a contribution to the study of the genericity of STICS for Quebec agrosystems. In addition to the climatic context, the originality of this work lies in the crops studied – spring barley and timothy – and the number of successive years of continuous simulations (without annual reinitialization). The predictive performances of STICS were analyzed for aboveground biomass production, N content and N export for i) a 31-year spring barley monoculture grown under two tillage systems and fertilized with two N sources (mineral N and liquid dairy manure); and ii) an 8-year timothy grassland, fertilized each year with four application N rates (0, 60, 120, 180 kg N ha-1). We used databases from two experimental field trials conducted by Agriculture and Agri-Food Canada.For the barley monoculture, the STICS calibration procedure required the adjustment of cultivar parameters in particular, thus confirming the genericity of most plant parameters defined in STICS. There is a good agreement between observed and predicted variables of interest with the various tillage systems and N sources during the 31 successive barley cropping years, but with greater dispersion for the N nutrition. Predictions of crop attributes were more accurate in years with rainfall close to the long-term average. For timothy grassland grown over 8 years, the agreement between observed and predicted values was satisfactory for the first harvest. STICS correctly simulated the positive effect of the N application rates on biomass production and plant N nutrition. Nevertheless, the predicted values were overestimated by the model in the absence of N fertilization. Except for this very specific situation, which is not representative of agronomic practices, STICS performed satisfactorily in the context of the two field experiments studied. In addition, STICS reproduced well decreasing trend in timothy productivity observed with the age of the sward. The results showed that this decrease in yield over time is strongly correlated with the reduction in metabolic reserve in the perennial organs.In conclusion, this thesis work has demonstrated the applicability and reliability of the STICS model for the long-term simulation of biomass production and N nutrition of spring barley and timothy under agropedoclimatic conditions in the Province of Quebec
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Norkaew, Saranya. "Soil Health Assessment of the Sanborn Field Long-term Experimental Study." Thesis, University of Missouri - Columbia, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13877157.
Abstract:
Soil health assessment uses a combination of potential indicators affecting soil processes to comprehensively monitor soil change, caused by cropping systems and soil management. The objectives of the study were to assess the effects of selected cropping systems, soil management and landscape slope positions on the soil health characteristics of the Sanborn Field long-term experimental study in Columbia, Missouri, United States. Soil samples were collected on each of four dates over two years (8th May 2014, 4th September 2014, 1st April 2016, and 18 th August 2016) from selected plots to address each objective, and these time samples were used as replications. Soil physical, chemical, and biological characteristics were analyzed in the laboratory for these samples to assess soil health using the Cornell Comprehensive Assessment of Soil Health (CASH) method. To assess soil health in this study, soil health scoring was determined used R-studio version 1.1.149 to relate the interaction of cropping systems, soil management, and slope positions. Most soil resources on Sanborn Field are a poorly-drained claypan soil classified as a Mexico silt loam (fine, smectitic, mesic Vertic Epiaqualf). In addition, soil samples collected from Tucker Prairie was used as a proxy for the original state of Sanborn Field soils. The first study was conducted to evaluate the effects of long-term cropping systems on soil health properties. The results from the characterization indicated that continuous timothy (Phleum pretense L.) and warm season grass treatments were classified with very high soil health scores, and the lowest score was found for continuous corn (Zea mays L.). In addition, results showed strong positive linear associations between soil organic carbon, total nitrogen, potentially mineralizable nitrogen, active carbon, microbial biomass, and water stable aggregates; while a strong negative linear correlation existed between each of these properties and bulk density. The second study was conducted to evaluate the effects of long-term annual applications of no fertilizer, full fertilizer, and manure on soil health measurements of selected cropping systems. Different cropping systems, including continuous corn, continuous wheat (Triticum aestivum L.), corn-wheat-red clover (Trifolium pretense L.) rotation, and corn-soybean (Glycine max L.)-wheat rotation treatments were used in this study. Results showed that annual dairy cow (Bos Taurus ) manure applications had the greatest effect on all soil health indicators and had the largest overall soil health score compared to full fertility and no fertilizer treatments. Moreover, continuous wheat with manure application presented the best combination of effects on soil properties with the largest score for most soil health indicators and an overall health score of 82 out of 100 classified as very high which is the best. The last study evaluated the effects of landscape slope positions on soil health properties of the long-term experiment. Results showed that the summit position had the highest overall soil health score while the lowest score was found on the shoulder position. However, there were no significant differences along the transect slope for water-stable aggregates and bulk density. There were significant differences along the transect for the biological properties such as soil organic carbon, active carbon, potentially mineralizable nitrogen, and microbial biomass. Results of this study illustrate the effect of selected variables on soil health and provide the recent addition of using biological characteristics to account for soil health properties. It is important to remember that this study of the long-term Sanborn Field experiment is just for a small-sized plot area. Future studies of soil management effects on soil health need to account for their own field conditions and their own unique environment.
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Winkelmann, Carola. "Predation effects of benthivorous fish on stream food webs – a large scale and long term field experiment." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1219311896723-68232.
Abstract:
It is a widely accepted assumption that fish predation controls structure and functioning of aquatic food webs. In the past, however, a large part of effort was concentrated on lakes and reservoirs. Thus, the knowledge about stream ecosystems is much more rudimentary than that for lakes in this respect. The aim of this thesis, therefore, was to describe and assess the effects of fish predation in natural stream ecosystems. For that purpose a reach scale field experiment was set up using an experimental stretch with benthivorous fish and a fishless reference stretch. A wide range of effects of the fish predators on their stream invertebrates prey was studied. To discriminate between lethal and sublethal predation effects, measuring the physiological status of the organisms seemed promising. However, before it was possible to decide whether or not environmental stress, such as predation, might affect the physiological status, the internal control as well as the seasonal and species-specific variability of the energy amount stored had to be assessed. Thus, the concentration and seasonal dynamics of the major energy storage components triglycerides and glycogen were measured in two species of mayflies (Rhithrogena semicolorata and Ephemera danica) with contrasting life cycle strategies. E. danica is a burrowing, semivoltine collector-gatherer, R. semicolorata is univoltine and scrapes periphyton from stones. Although triglycerides are the major energy reserve in both species throughout the whole larval development (> 84 % of total energy storage) their seasonal dynamic differed considerably. In R. semicolorata the triglyceride concentration declined during the last weeks prior to emergence in both sexes. The same pattern was found in female larvae of E. danica, but not in male E. danica. It is suggested that females use triglycerides in the last larval stages for egg maturation, which is completed in the last larval instar. In male E. danica the triglyceride concentrations remained high until emergence, presumably due to their high energy demands as adults for their swarming flights and mating. The difference in seasonal variation of triglycerides between E. danica and R. semicolorata shows the influence of environmental factors on the dynamics of storage components. E. danica lived in a very stable environment (within the substratum). Therefore the dynamic of energy storage components was optimised with respect to maximal reproduction. R. semicolorata on the other hand, suffered from hostile environmental factors such as predation or food limitation due to low periphyton biomass after leaf sprout and following light limitation in spring. Consequently, the concentration of storage components decreased during spring. One conclusion from this study was that the measurement of storage components might reveal sublethal predation effects. However, season and sex of the organisms are important factors as well and have to be considered in the sampling design. To analyse sublethal predation effects behavioural changes due to the presence of benthivorous fish were measured. Drift as a low-energy cost means of migration may enable stream invertebrates to leave risky habitats or may even be a direct escape reaction after a predator encounter. While the control of drift activity by predators has received considerable interest from many researchers, it remains still unclear whether predators reduce or increase drift activity. Drift activity of stream invertebrates was influenced significantly by the presence or absence the two benthivorous fish species gudgeon (Gobio gobio) and stone loach (Barbatula barbatula). Contrary to previous studies gudgeon and stone loach reduced invertebrate drift density and drift activity of Baetis rhodani rather than inducing higher night-time drift. Further, species composition of the invertebrate drift differed significantly between the two stretches. A further conclusion from this study is therefore that drift is not generally a mechanism of active escape from benthos-feeding fish, as previously assumed. In addition, the reduced drift activity in the fish stretch might result in a compensation of the consumptive losses due to fish predation. Thus, in this study design the effects of fish predation on invertebrate community might be underestimated. To detect predation effects on the food web structure the reactions of the grazing mayfly Rhithrogena semicolorata and the shredding amphipod Gammarus pulex to strong predation by benthivorous fish were compared. It has been hypothesised that shredders are generally less vulnerable to fish predation and therefore less likely to be predation-controlled than grazers, because the latter are visible to the predators during their feeding on stone surfaces, while shredders may hide between leaves during foraging. Biomass of G. pulex was significantly reduced in the fish stretch while that of R. semicolorata was not. Since approximately 91 % of the annual production of G. pulex but only 12 % of R. semicolorata production was consumed by benthivorous gudgeon, the observed difference of G. pulex biomass between the fish and reference reach is likely due to a lethal predation effect. However, no sublethal predation effects such as reduced concentration of storage components (triglycerides, glycogen) or reduced reproductive success were observed for both species. Hence, in contrast to the initial hypothesis, in the studied stream the shredder was top-down-controlled, while the grazer was not. It is concluded that top-down control depends on the ecological characteristics of a specific predator-prey pair rather than on trophic guild of the prey. To assess the predation effects on the life history of merolimnic insects and its consequences on fecundity the larval development and emergence of R. semicolorata was studied. It was possible to show lethal and sublethal effects of predation by benthivorous fish (Gobio gobio, Barbatula barbatula). Predation consequently resulted in changes of larval development and population fitness. The presence of two benthivorous fish species (gudgeon and stone loach) led to slower larval development and a delayed emergence. However, no differences in the adult size and fecundity between the fish reach and the reference were observed. Nevertheless, the longer time spent in the larval phase resulted in a higher mortality and therefore in a lower mean population fitness. The presence of gudgeon alone, however, did not seem to influence larval development, growth or time of emergence and consequently fecundity. Further, strong lethal impact of gudgeon could not be detected. Thus, the population fitness measured as the product of adult density and egg number was not reduced by gudgeon alone. It is assumed that the stronger lethal impact in the combined fish experiment is caused mainly by stone loach because the proportion of mayfly consumption by stone loach to mayfly production shortly before emergence was higher than the proportion related to gudgeon. Thus another conclusion is that 1) the impact of predation seems to differ for the fish species and 2) lethal effects have a stronger impact on the population survival than life history changes. Combining the results mentioned above leads to the assumption that predation by benthivorous fish has the potential to shape invertebrate communities and food webs in streams. It was possible to show reductions of benthic densities and mean population fitness. The strength of trophic interactions seemed to be specific for the single predator-prey pairs here. Finally, it can be stated that contrary to previous assumptions consumption of the fish predators seemed to be more important for the prey populations than sublethal predation effects.
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Winkelmann, Carola. "Predation effects of benthivorous fish on stream food webs – a large scale and long term field experiment." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23819.
Abstract:
It is a widely accepted assumption that fish predation controls structure and functioning of aquatic food webs. In the past, however, a large part of effort was concentrated on lakes and reservoirs. Thus, the knowledge about stream ecosystems is much more rudimentary than that for lakes in this respect. The aim of this thesis, therefore, was to describe and assess the effects of fish predation in natural stream ecosystems. For that purpose a reach scale field experiment was set up using an experimental stretch with benthivorous fish and a fishless reference stretch. A wide range of effects of the fish predators on their stream invertebrates prey was studied. To discriminate between lethal and sublethal predation effects, measuring the physiological status of the organisms seemed promising. However, before it was possible to decide whether or not environmental stress, such as predation, might affect the physiological status, the internal control as well as the seasonal and species-specific variability of the energy amount stored had to be assessed. Thus, the concentration and seasonal dynamics of the major energy storage components triglycerides and glycogen were measured in two species of mayflies (Rhithrogena semicolorata and Ephemera danica) with contrasting life cycle strategies. E. danica is a burrowing, semivoltine collector-gatherer, R. semicolorata is univoltine and scrapes periphyton from stones. Although triglycerides are the major energy reserve in both species throughout the whole larval development (> 84 % of total energy storage) their seasonal dynamic differed considerably. In R. semicolorata the triglyceride concentration declined during the last weeks prior to emergence in both sexes. The same pattern was found in female larvae of E. danica, but not in male E. danica. It is suggested that females use triglycerides in the last larval stages for egg maturation, which is completed in the last larval instar. In male E. danica the triglyceride concentrations remained high until emergence, presumably due to their high energy demands as adults for their swarming flights and mating. The difference in seasonal variation of triglycerides between E. danica and R. semicolorata shows the influence of environmental factors on the dynamics of storage components. E. danica lived in a very stable environment (within the substratum). Therefore the dynamic of energy storage components was optimised with respect to maximal reproduction. R. semicolorata on the other hand, suffered from hostile environmental factors such as predation or food limitation due to low periphyton biomass after leaf sprout and following light limitation in spring. Consequently, the concentration of storage components decreased during spring. One conclusion from this study was that the measurement of storage components might reveal sublethal predation effects. However, season and sex of the organisms are important factors as well and have to be considered in the sampling design. To analyse sublethal predation effects behavioural changes due to the presence of benthivorous fish were measured. Drift as a low-energy cost means of migration may enable stream invertebrates to leave risky habitats or may even be a direct escape reaction after a predator encounter. While the control of drift activity by predators has received considerable interest from many researchers, it remains still unclear whether predators reduce or increase drift activity. Drift activity of stream invertebrates was influenced significantly by the presence or absence the two benthivorous fish species gudgeon (Gobio gobio) and stone loach (Barbatula barbatula). Contrary to previous studies gudgeon and stone loach reduced invertebrate drift density and drift activity of Baetis rhodani rather than inducing higher night-time drift. Further, species composition of the invertebrate drift differed significantly between the two stretches. A further conclusion from this study is therefore that drift is not generally a mechanism of active escape from benthos-feeding fish, as previously assumed. In addition, the reduced drift activity in the fish stretch might result in a compensation of the consumptive losses due to fish predation. Thus, in this study design the effects of fish predation on invertebrate community might be underestimated. To detect predation effects on the food web structure the reactions of the grazing mayfly Rhithrogena semicolorata and the shredding amphipod Gammarus pulex to strong predation by benthivorous fish were compared. It has been hypothesised that shredders are generally less vulnerable to fish predation and therefore less likely to be predation-controlled than grazers, because the latter are visible to the predators during their feeding on stone surfaces, while shredders may hide between leaves during foraging. Biomass of G. pulex was significantly reduced in the fish stretch while that of R. semicolorata was not. Since approximately 91 % of the annual production of G. pulex but only 12 % of R. semicolorata production was consumed by benthivorous gudgeon, the observed difference of G. pulex biomass between the fish and reference reach is likely due to a lethal predation effect. However, no sublethal predation effects such as reduced concentration of storage components (triglycerides, glycogen) or reduced reproductive success were observed for both species. Hence, in contrast to the initial hypothesis, in the studied stream the shredder was top-down-controlled, while the grazer was not. It is concluded that top-down control depends on the ecological characteristics of a specific predator-prey pair rather than on trophic guild of the prey. To assess the predation effects on the life history of merolimnic insects and its consequences on fecundity the larval development and emergence of R. semicolorata was studied. It was possible to show lethal and sublethal effects of predation by benthivorous fish (Gobio gobio, Barbatula barbatula). Predation consequently resulted in changes of larval development and population fitness. The presence of two benthivorous fish species (gudgeon and stone loach) led to slower larval development and a delayed emergence. However, no differences in the adult size and fecundity between the fish reach and the reference were observed. Nevertheless, the longer time spent in the larval phase resulted in a higher mortality and therefore in a lower mean population fitness. The presence of gudgeon alone, however, did not seem to influence larval development, growth or time of emergence and consequently fecundity. Further, strong lethal impact of gudgeon could not be detected. Thus, the population fitness measured as the product of adult density and egg number was not reduced by gudgeon alone. It is assumed that the stronger lethal impact in the combined fish experiment is caused mainly by stone loach because the proportion of mayfly consumption by stone loach to mayfly production shortly before emergence was higher than the proportion related to gudgeon. Thus another conclusion is that 1) the impact of predation seems to differ for the fish species and 2) lethal effects have a stronger impact on the population survival than life history changes. Combining the results mentioned above leads to the assumption that predation by benthivorous fish has the potential to shape invertebrate communities and food webs in streams. It was possible to show reductions of benthic densities and mean population fitness. The strength of trophic interactions seemed to be specific for the single predator-prey pairs here. Finally, it can be stated that contrary to previous assumptions consumption of the fish predators seemed to be more important for the prey populations than sublethal predation effects.
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Roman, Erika. "Maternal Separation in Rats : An Experimental Model for Long-Term Effects of Early Life Experiences on Neurochemistry, Voluntary Ethanol Intake and Exploration and Risk Assessment Behavior." Doctoral thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4465.
Abstract:
The period of early life is important for the development of individual brain function and behavior. Human studies have shown altered vulnerability to develop psychopathology and/or excessive drug intake, possibly leading to dependence, as a consequence of early life experiences. In the present thesis, maternal separation (MS), an experimental model for studies of early environmental influences, was used to investigate long-term effects on neurochemistry, voluntary ethanol intake and exploration and risk assessment behavior in rats. Rat pups were assigned to one of three different rearing conditions: daily 15 min (MS15) or 360 min (MS360) of MS and normal animal facility rearing (AFR) during the first three weeks of life. Measurements of adult endogenous opioid peptide levels, opioid- and dopamine receptor density revealed minor MS-induced effects on the opioid system whereas interesting alterations were found in dopamine receptor density. Long-term effects on voluntary ethanol intake showed distinct MS-induced alterations in male Wistar and ethanol-preferring AA (Alko, Alcohol) rats. Female Wistar rats were unaffected, indicating sex differences in the effects of MS on ethanol intake. Male MS15 rats generally had a slower acquisition phase and a low subsequent ethanol intake whereas male MS360 rats had a high ethanol intake. MS15 is therefore suggested to protect against a high voluntary ethanol intake in male rats whereas MS360 may serve as a risk factor. The recently established concentric square field test indicated alterations in risk assessment as well as an increased exploratory drive and somewhat higher risk-taking behavior in adult MS360 rats, while minor effects were seen in MS15 rats. Altogether, these results demonstrate that environmental influences during the period of early life can have long-term effects on neurochemistry and behavior. Of special interest is the finding that MS altered the inherited high ethanol intake in adult ethanol-preferring AA rats.
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Bakker, Eleanor. "The impact of plant growth and potassium uptake on clay minerals in soil." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU012/document.
Abstract:
Le potassium est un nutriment essentiel à la croissance et au développement des plantes. Les minéraux argileux dans les sols représentent un important réservoir de K disponible pour les plantes. L'extraction de K fixé à partir de l'espace interfoliaire des minéraux micacés 2:1 peut entraîner une augmentation de la distance feuillet à feuillet qui peut être mesurée par diffraction des rayons X . Des échantillons de l'expérience Morrow Plots continue avec du maïs (C) ou du maïs-avoine-foin (R), provenant de sous-parcelles fertilisées (F) et non fertilisées (U) pour les années 1904, 1957, 1980, 1997 et 2013-2014, ont été soumis au fractionnement granulométrique séquentiel pour obtenir la fraction limoneuse (50-2 um) et les sous-fractions argileuses (2-0,2, 0,2-0,05 et <0,05 um). Les résultats granulométriques montrent une hétérogénéité significative malgré la petite taille de la MP, et un gain de sous-fraction < 0,05 um avec le temps. La modélisation des diagrammes de diffraction des rayons X a été effectuée pour obtenir une identification concluante de l'assemblage de minéraux argileux et évaluer l'impact de 110 ans d'agriculture continue et de différentes pratiques agronomiques. Un assemblage complexe de minéraux argileux a été identifié avec jusqu'à onze contributions différentes nécessaires pour reproduire les données expérimentales de sous-fractions de moins de 2 um, y compris jusqu'à six couches mixtes d'illite-smectite-chlorite. L'analyse de phase quantitative pour toutes les sous-parcelles et toutes les années, a montré que l'assemblage minéral du MP est similaire entre les différentes sous-parcelles, quel que soit le traitement agronomique. Aucune preuve significative d'altération ou de transformation des phases minérales argileuses n'a été observée au fil du temps. La nature dioctaédrique des minéraux argileux de la MP désavantage l'extraction du K et donc la dissolution est le mécanisme privilégié pour l'absorption du K et la perte de sous-fractions 2-0,2 et 0,2-0,05 um est attribuée à ce processusPotassium is an essential nutrient for plant growth and development. Clay minerals in soils represent an important reservoir of plant-available K. Extraction of fixed K from the interlayer space of micaceous 2:1 minerals can lead to an increase in the layer-to-layer distance which can be measured by X-ray diffraction. Samples from the Morrow Plots continuous corn (C) and corn-oats-hay (R) experiment, from fertilised (F) and non-fertilised (U) subplots for the years 1904, 1957, 1980, 1997 and 2013-2014 were subjected to sequential size-fractionation to obtain the silt fraction (50-2 um) and clay-sized subfractions (2-0.2, 0.2-0,05 and <0.05 um). Granulometric results show siginificant heterogeneity despite the small size of the MP, and a gain in <0.05 um subfraction with time. Full-profile fitting of X-ray diffraction patterns was performed to obtain conclusive identification of the clay mineral assemblage and assess the impact of 110-years of continuous agriculture and different agronomic practices. A complex clay mineral assemblage was identified with up to eleven different contributions necessary to reproduce the experimental data of <2 um subfractions, including up to six illite-smectite-chlorite mixed-layers. Quantitative phase analysis for all subplots and years showed that the mineral assemblage of the MP is similar between different subplots, regardless of agronomic treatment. No significant evidence of alteration or transformation of clay mineral phases was observed over time. The dioctahedral nature of the clay minerals of the MP disfavours K-extraction and thus dissolution is the favoured mechanism for K-uptake and the loss of 2-0.2 and 0.2-0.05 um subfractions is attributed to this process
10
Genero, Magalí Martí. "Microbial Communities in Boreal Peatlands : Responses to Climate Change and Atmospheric Nitrogen and Sulfur Depositions." Doctoral thesis, Linköpings universitet, Tema Miljöförändring, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-137487.
Abstract:
Myrmarker har en stor roll i regleringen av den globala kolbalansen och koncentrationerna av koldioxid och metan i atmosfären, vilket gör dem till speciellt viktiga ekosystem ur ett klimatförandringsperspektiv. Förändringar av myrmarker genom naturlig utveckling eller antropogen påverkan kan därför få långtgående störningar av myrars klimatreglerande funktion. Mikroorganismer har en avgörande roll i biogeokemiska processer genom att t ex bryta ned organisk material i mark och därmed styra kolets kretslopp. För att förstå hur myrsystemen reagerar på störningar är det därför väsentligt att veta hur mikroorganismsamhällena reagerar genom förändringar i sammansättning och biogeokemisk aktivitet. Målet för studierna, som ligger till grund för denna avhandling, var att undersöka hur mikroorganismsamhällen i myrar reagerar på uppvärmning genom klimatförändring och ökade kväve- (N) och svavel- (S) halter i nederbörd. High through-put sekvensering användes för att studera taxonomiska och funktionella egenskaper hos mikroorganismerna i myrar och quantative PCR användes för att mer specifikt studera de metanbildande arkeorna. Två fältkampanjer vardera omfattande tre ombrotrofa myrar med olika klimatförhållanden och olika mängder N och S inederbörden användes för att undersöka lokala och storskaliga effekter på myrars mikrobiella samhällen. Resultaten visade att latudinell variation i geoklimatologiska förhållanden (temperatur ochnederbördsmängd) och deposition av näringsämnen hade en påverkan på sammansättningen av de mikrobiella samhällena och aktiva metanbildare förr än variationen i den kemiska miljön inom varje specifik myr. Myrväxtsamhällenas sammansättning för en specifik myr visades sig i stor utsträckning styra sammansättningen av motsvarande mikrobiella samhälle i torvprofilen. Detta framgick klart av i en analys av samexisterande nätverk av mikroorganismsamhällen och motsvarande växtsamhällen i en studie av tre geografiskt skilda myrar med olika kvävedeposition. Effekterna av klimatförändring och nederbörd med olika mängder av N och S studerades mer specifikt genom att analysera de mikrobiellasamhällena i ett långliggande (18 år) försök. Påverkan av var och en av dessa manipulationer antingen förstärktes eller minskades, när de förekom i kombinationer. Ökad kvävedeposition var den faktor som hade starkast effekt. De långvariga störningarna medförde stora förändringar i den mikrobiella taxonomin inom samhällena. Detta återspeglades dock inte i den fysiologiska kapaciteten, vilket visar att det finns en stark buffring i myrarnas mikrobiella funktion. Detta tyder på att framtida utveckling av myrar i relation till olika störningar sannolikt inte kommer att påverka myrarnas roll för kolbalans och växthusgasutbyte med atmosfären.Peatlands play a substantial role in regulating the global carbon balance and concentrations of the greenhouse gases CO2 and CH4 in the atmosphere, and are thus of utmost importance from a climate change perspective. Any changes of peatland functions due to natural or anthropogenic perturbations may result in changes in these ecosystem services. Soil microbial communities are essential drivers of biogeochemical processes, including the carbon cycle. In order to fully understand the effect of environmental perturbations on peatland functions, it is essential to understand how microbial communities are affected. The aim of the research presented in this thesis was to investigate the responses of the peat microbial communities to climate change and increased precipitation of nitrogen(N) and sulfur (S) compounds. High-throughput sequencing approaches were used to investigate the taxonomic and functional composition of microbial communities, and quantitative PCR was used to specifically target the methanogen community. Two field studies including three ombrotrophic peatlands each that differed in climatological conditions and atmospheric N and S depositions, were used to investigate and compare the effect of large- and local-scale environmental conditions on microbial communities. The results show that the variation in geo-climatological (temperature and precipitation) and atmospheric deposition conditions along the latitudinal gradient modulate the peat microbial community composition and the abundance of active methanogens to a greater extent thansite-related microhabitats. Furthermore, a tight coupling between the plant community composition of a site and the composition of its microbial community was observed, and was found to be mainly driven by plants rather than microorganisms. These co-occurrence networks are strongly affected by seasonal climate variability and the interactions between species in colder areas are more sensitive to climate change. The long-term effects of warming and increased N and S depositions on the peat microbial communities were further investigated using an 18-year in-situ peatland experiment simulating these perturbations. The impacts of each of these perturbations on the microbial community were found to either multiply or counteract one another, with enhanced N deposition being the most important factor. While the long-term perturbations resulted in a substantial shift in the taxonomic composition of microbial communities, only minor changes occurred in genome-encoded functional traits, indicating a functional redundancy. This could act as a buffer maintaining ecosystem functioning when challenged by multiple stressors, and could limit future changes in greenhouse gases and carbonexchange.
Books on the topic "Long-term field experiments":
1
Bailey, David M. Long term field test results of experimental EPDM and PUF roofing. Champaign, Ill: US Army Corps of Engineers, Construction Engineering Research Laboratory, 1990.
2
Cook, Charles Michael. The experimental induction of the "sensed presence" by the application of magnetic fields whose temporal patterns simulate long-term potentiation. Sudbury, Ont: Laurentian University, Department of Psychology, 1996.
3
The Effects of tributyltin (TBT) accumulation on adult dog-whelks, 'nucella lapillus': Long-term field and laboratory experiments. Cambridge: Cambridge University Press, 1987.
4
Gibson, John, David McKenzie, Halahingano Rohorua, and Steven Stillman. The Long-Term Impact of International Migration on Economic Decision-Making: Evidence from a Migration Lottery and Lab-in-the-Field Experiments. World Bank, Washington, DC, 2016. http://dx.doi.org/10.1596/1813-9450-7848.
5
BURAVTSEVA, T. V., I. N. PERCHUK, A. E. SOLOVEVA, M. V. GURKINA, and G. P. EGOROVA. COMMON BEAN (PHASEOLUS VULGARIS L.): ASSESSMENT OF PROTEIN CONTENT IN SEEDS WITH BRIEF DESCRIPTION OF USEFUL AGRONOMIC TRAITS. N.I. Vavilov All-Russian Institute of Plant Genetic Resources, 2021. http://dx.doi.org/10.30901/978-5-907145-73-3.
Abstract:
The catalogue contains the results of protein content assessment in seeds of 216 common bean (Phaseolus vulgaris L.) accessions from the VIR plant genetic resources collection. The data of a long-term study with mean values of characters for each accession are presented. The study of main agronomic characters in the accessions was conducted from 2004 through 2018 in the experimental fields at Astrakhan Experiment Station of VIR. The accessions are described employing eight morphological and agronomic characters important for breeding practice. This catalogue is intended to serve as a tool in source material selection for further breeding process. It may prove helpful for plant breeders and grain legume experts.
6
Tesler, Michael, and John Zaller. The Power of Political Communication. Edited by Kate Kenski and Kathleen Hall Jamieson. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780199793471.013.003.
Abstract:
Most scholars agree that the effects of mass communication are more than minimal. We find, however, that most communication effects are short-lived, involve mainly weakly held attitudes, and produce no political consequences. Party cues conveyed in mass communication can change attitudes, but usually weakly held ones; when individuals hold strong views, they often change parties rather than change attitudes. Non-partisan communication may not durably change any attitudes, even weakly held ones. These conclusions, derived from field studies rather than laboratory experiments, raise the old minimal effects question in a new form: How politically important are the effects of mass communication? Our answer is that it depends on context. Short-term communication effects can be quite consequential if they occur close to a relevant political decision, such as an election or congressional vote. Communication that continues over a long period of time, such as messages carrying the value of racial equality, may also be important. Short-term or episodic communication that aims to produce a generally informed citizenry, independent of any political decision, may have little importance.
7
Farnsworth, John Seibert, and Thomas Lowe Fleischner. Nature beyond Solitude. Cornell University Press, 2020. http://dx.doi.org/10.7591/cornell/9781501747281.001.0001.
Abstract:
The field notes taken for this book are not only about nature, but from nature as well. The book lets the reader peer over the author'shoulder as he takes his notes. The reader follows him to a series of field stations where he teams up with scientists, citizen scientists, rangers, stewards, and graduate students engaged in long-term ecological study, all the while scribbling down what he sees, hears, and feels in the moment. The field stations are located at Hastings Natural History Reservation, studying acorn woodpeckers; Santa Cruz Island Reserve, studying island foxes; Golden Gate Raptor Observatory, hawkwatching; H. J. Andrews Experimental Forest, recording a forest log for two weeks through the Spring Creek Project; and North Cascades Environmental Learning Center, which was built as mitigation for the environmental harm caused by the hydroelectric dam. The book explores how communal experiences of nature might ultimately provide greater depths of appreciation for the natural world.
8
Warner, H. R. “Hal.” The Reservoir Engineering Aspects of Waterflooding. Society of Petroleum Engineers, 2015. http://dx.doi.org/10.2118/9781613994214.
Abstract:
The first edition of The Reservoir Engineering Aspects of Waterflooding was published in 1970 and written by Forrest F. Craig, Jr. At the time of publication, much of the theory of oil displacement by water had been developed and many laboratory studies completed; however, the ability to perform computer modeling of 3D fluid flow in reservoirs with complex geologic depositions was in its infancy. In addition, several of the earliest, large-scale field applications of pattern waterflooding had begun, but long-term performance results were not yet known, and various infill drilling programs had yet to be implemented. This second edition reviews the fundamentals of waterflooding theory, and the experimental studies undertaken to understand the water displacement of oil in one, two, and three dimensions.
9
Havstad, Kris M., Laura F. Huenneke, and William H. Schlesinger, eds. Structure and Function of a Chihuahuan Desert Ecosystem. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195117769.001.0001.
Abstract:
The Jornada Basin LTER is located in the Chihuahuan Desert, the largest in North America. This region of south central New Mexico has a history of nearly 100 years as the basis for scientific research. This work gives a thorough, encompassing review of the tremendous array of observations resulting from experiments conducted in this ecosystem. Beginning with thorough descriptions of the most salient features of the region, the book then reviews a wide range of archived and active data sets on a diversity of biotic and abiotic features. It next presents a syntheses of important topics including livestock grazing and remediation efforts. A concluding chapter provides a synthesis of the principles that have emerged from this body of work, and how these relate to the broader fields of ecology and natural resource management. It concludes with recommendations for future research directions. The insightful views expressed in this volume should guide management of arid landscapes globally. This is the sixth volume in the Long Term Ecological Network Series.
10
Xue, Yongkang, Yaoming Ma, and Qian Li. Land–Climate Interaction Over the Tibetan Plateau. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.592.
Abstract:
The Tibetan Plateau (TP) is the largest and highest plateau on Earth. Due to its elevation, it receives much more downward shortwave radiation than other areas, which results in very strong diurnal and seasonal changes of the surface energy components and other meteorological variables, such as surface temperature and the convective atmospheric boundary layer. With such unique land process conditions on a distinct geomorphic unit, the TP has been identified as having the strongest land/atmosphere interactions in the mid-latitudes.Three major TP land/atmosphere interaction issues are presented in this article: (1) Scientists have long been aware of the role of the TP in atmospheric circulation. The view that the TP’s thermal and dynamic forcing drives the Asian monsoon has been prevalent in the literature for decades. In addition to the TP’s topographic effect, diagnostic and modeling studies have shown that the TP provides a huge, elevated heat source to the middle troposphere, and that the sensible heat pump plays a major role in the regional climate and in the formation of the Asian monsoon. Recent modeling studies, however, suggest that the south and west slopes of the Himalayas produce a strong monsoon by insulating warm and moist tropical air from the cold and dry extratropics, so the TP heat source cannot be considered as a factor for driving the Indian monsoon. The climate models’ shortcomings have been speculated to cause the discrepancies/controversies in the modeling results in this aspect. (2) The TP snow cover and Asian monsoon relationship is considered as another hot topic in TP land/atmosphere interaction studies and was proposed as early as 1884. Using ground measurements and remote sensing data available since the 1970s, a number of studies have confirmed the empirical relationship between TP snow cover and the Asian monsoon, albeit sometimes with different signs. Sensitivity studies using numerical modeling have also demonstrated the effects of snow on the monsoon but were normally tested with specified extreme snow cover conditions. There are also controversies regarding the possible mechanisms through which snow affects the monsoon. Currently, snow is no longer a factor in the statistic prediction model for the Indian monsoon prediction in the Indian Meteorological Department. These controversial issues indicate the necessity of having measurements that are more comprehensive over the TP to better understand the nature of the TP land/atmosphere interactions and evaluate the model-produced results. (3) The TP is one of the major areas in China greatly affected by land degradation due to both natural processes and anthropogenic activities. Preliminary modeling studies have been conducted to assess its possible impact on climate and regional hydrology. Assessments using global and regional models with more realistic TP land degradation data are imperative.Due to high elevation and harsh climate conditions, measurements over the TP used to be sparse. Fortunately, since the 1990s, state-of-the-art observational long-term station networks in the TP and neighboring regions have been established. Four large field experiments since 1996, among many observational activities, are presented in this article. These experiments should greatly help further research on TP land/atmosphere interactions.
Book chapters on the topic "Long-term field experiments":
1
Németh, T. "Nitrogen balances in long-term field experiments." In Fertilizers and Environment, 31–37. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1586-2_7.
2
Emnova, E. "Biochemical Parameters of Arable Chernozem in Long-Term Field Experiments." In Soil as World Heritage, 45–55. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6187-2_7.
3
Körschens, Martin. "Long-Term Field Experiments (LTEs)—Importance, Overview, Soil Organic Matter." In Innovations in Landscape Research, 215–31. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-67448-9_8.
4
Libershteyn, J. "The Beginnings of Long-Term Field Experiments on Crop Rotations at Balti." In Soil as World Heritage, 171–74. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6187-2_18.
5
Kihanda, F. M., and G. P. Warren. "Management of Soil Fertility in a Long-Term Field Trial of Semi-arid Kenya." In Lessons learned from Long-term Soil Fertility Management Experiments in Africa, 85–103. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-2938-4_5.
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Hera, C. "Long-Term Field Experiments with Fertilizers in Romania: Their Relevance to Sustainable Agriculture." In Soil as World Heritage, 159–69. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6187-2_17.
7
Andrieş, S., V. Lungu, and N. Leah. "Long-Term Field Experiments as a Foundation for Conserving and Enhancing Soil Fertility." In Soil as World Heritage, 201–7. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6187-2_20.
8
Senikovskaya, I. "Biota of Typical Chernozem Under Different Land Uses in Long-Term Field Experiments." In Soil as World Heritage, 21–27. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6187-2_4.
9
Campbell, C. A., Y. w. Jame, O. O. Akinremi, and H. J. Beckie. "Evaluating Potential Nitrogen Mineralization for Predicting Fertilizer Nitrogen Requirements of Long-Term Field Experiments." In SSSA Special Publications, 81–100. Madison, WI, USA: Soil Science Society of America, Inc., American Society of Agronomy, Inc., 2015. http://dx.doi.org/10.2136/sssaspecpub40.c5.
10
Alcock, R. E., and K. C. Jones. "Long-Term Field Experiments and Implications for Soil Quality Assessment with Respect to Organic Contaminants." In Soil Quality, Sustainable Agriculture and Environmental Security in Central and Eastern Europe, 115–24. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4181-9_9.
Conference papers on the topic "Long-term field experiments":
1
Melkumyan, Mariam, Nicole Lookfong, Wesley Raup-Konsavage, Kent Vrana, and Yuval Silberman. "Effects of cannabidiol with and without other cannabinoids and terpenes on short-term and long-term stress-related behaviors." In 2022 Annual Scientific Meeting of the Research Society on Marijuana. Research Society on Marijuana, 2022. http://dx.doi.org/10.26828/cannabis.2022.02.000.02.
Abstract:
Introduction: Stress-related disorders, such as anxiety and post-traumatic stress disorder, are a primary reason for treatment (and self-medication) with medical cannabis products. Research suggests endocannabinoids regulate neurotransmitters involved in stress but whether phytocannabinoids such as cannabidiol (CBD) reduce stress behaviors is not fully established. To that end, we sought to examine how CBD with and without other cannabinoids or terpenes might alter behavior in mouse models of short-term and long-term responses to acute stressors. Methods: For short-term stress responses, adult male C57Bl/6J mice received a 30-60-minute restraint stress followed by testing with open field and light-dark box tests. Mice were treated with vehicle, CBD (10mg/kg), or CBD with low dose delta-9-tetrahydrocanabinol (THC, 2.5mg/kg and 7.5 mg/kg CBD for 10mg/kg total cannabinoid content) 45-60 minutes prior to stress exposure. For long-term stress behavior, mice underwent conditioned place avoidance to restraint plus predator odor contexts, with controls receiving individual stressors or no stress. Avoidance to the stress paired context was examined 1, 7, and 28 days later. Groups received vehicle, CBD (3.07 mg/ml CBD, 3mg/kg cannabigerol, low terpenes), CBD+THClo-terp (3.07 mg/ml CBD, 3mg/kg cannabigerol, 0.76 mg/ml THC, low terpenes), or CBD+THChi-terp (3.29 mg/ml CBD, 3mg/kg cannabigerol, 0.76 mg/ml THC, high terpenes) 30-45 minutes after stress exposure. Researchers were blinded to treatment conditions during all analyses. Results: In the short-term experiments, mice treated with CBD trended towards an increase in the time spent and decreased latency to enter the light side of the light-dark box compared to vehicle, suggesting reduced anxiety-like behaviors. Additionally, CBD treated mice showed reductions in freezing, immobility time, and latency to enter the center of the open field compared to vehicle treated mice, with no differences in the time spent in the center of the field. CBD+THC treatment showed no significant differences compared to vehicle. In the long-term experiments, mice exposed to restraint plus predator odor showed reduced time spent in the stress paired chamber on days 1, 7, and 28 post-stress, although there did appear to be stress susceptible and resilient mice in this paradigm. Avoidance behaviors were not seen when stressors were presented individually or if no stress was used. In this paradigm, CBD+THClo-terp was the only treatment to reduce avoidance behavior at the post-stress time points tested. Conclusions: These results suggest that CBD has a differential effect on anxiety-like behaviors based on type of stress, post-stress timing of behavioral testing, and CBD/THC/cannabigerol/terpene content. Further studies are needed to uncover the effect of phytocannabinoids on short-term and long-term stress responses as well as related neurotransmitters and circuitries driving these effects.
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Kumasaka, J., Y. Kaito, A. Goto, D. Ito, H. Kitagawa, T. Nogami, and S. Murakami. "First Nanoparticle-Based EOR Project in Japan : Field Pilot Test." In SPE Improved Oil Recovery Conference. SPE, 2024. http://dx.doi.org/10.2118/218278-ms.
Abstract:
Abstract Nanoparticle-based enhanced oil recovery (Nano-EOR) is an improved waterflooding assisted by nanoparticles dispersed in injection water (nanofluid). Although Nano-EOR has been revealed to become a promising technique from many laboratory experiments, field applications are still limited. This paper discusses the first Nano-EOR field pilot tests for the Sarukawa oil field in Japan. The field pilot tests were divided into two stages: short-term injection test and long-term inter-well test. The short-term injection test was performed mainly to investigate the effects of nanofluid on the well injectivity. Nanofluid was injected into an existing water injection line by an air-driven liquid pump at a concentration of 0.5 wt. % which was optimized in the series of our study. The result of the short-term injection test showed that the nanoparticles used in this study can be injected into the target formation without any damage when the concentration is properly controlled. For the long-term inter-well test, 0.5 wt. % nanofluid was injected into the injection well for two months to validate the increase in oil production. The production behavior was monitored frequently and compared to the reference decline curve. Inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis of the production fluid was also performed to detect the breakthrough of the injected nanoparticles. Although nanoparticles were not detected in the producer well, the oil production rate showed a positive deviation from the estimated baseline decline curve, suggesting an increase in oil production due to the nanoparticles injected from the injector. This paper has made a comprehensive discussion and summary of the challenges based on the current status of the long-term inter-well test. This study established a simple pilot scheme for Nano-EOR and this will contribute to the upcoming Nano-EOR projects.
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Samarkin, Yevgeniy, Murtada Saleh Aljawad, Theis Ivan Solling, Abduljamiu Olalekan Amao, Murtadha J. AlTammar, and Khalid M. Alruwaili. "Diammonium Hydrogen Phosphate Treatment for Sustaining Long-Term Acid Fracture Conductivity of Chalk Formations." In SPE Annual Technical Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/214856-ms.
Abstract:
Abstract The reactive acid, injected into the formation during acid fracturing operations, etches the surfaces of the fracture, generating asperities that keep the fracture conductive. However, the stresses acting on the fracture tend to close it, destroying the asperities. Asperities' destruction is especially severe in soft carbonate formations such as chalk. This work focuses on improving the long-term acid fracture conductivity sustenance by hardening the chalk rocks through chemical treatment. Diammonium Hydrogen Phosphate (DAP) is applied to harden chalk slabs treated with 10% HCl acid in this work. Treated slabs are inserted in the API conductivity device that allows for measuring the conductivity of the fracture. The conductivity of the fracture treated by DAP after acid injection is measured at different stresses and compared with the conductivity of the acidized fracture with no DAP treatment. Furthermore, the additional analysis is conducted to observe the changes in the roughness and hardness of the samples before and after treatments. The results demonstrated that the hardness of the chalk samples was decreased by 30 - 40% after acidizing. However, the subsequent treatment of the acidized samples with the DAP solution restored their original hardness. Moreover, the hardened samples were more deformation-resistant to the applied stresses based on Linear Variable Differential Transformers'(LVDT) measurements. The conductivity of the DAP-treated fracture decreased less abruptly with applied stresses (up to 2,500 psi) compared to the acidized but untreated fracture. As a result, the ultimate conductivity of a DAP-treated fracture was 60 md-ft, which was significantly higher than the conductivity of the untreated fracture that constituted 8 mdft. Additional long-term conductivity experiments were conducted over time (6 days) while applying the fixed stress. These experiments have shown that the decline in the conductivity of treated fracture is less severe compared to untreated fracture. It was noted that the plateau value of long-term fracture conductivity for the treated samples was significantly higher than for the untreated case. This work presents a novel approach to sustaining acid fracture conductivity in soft chalk formations through chemical treatment with a DAP solution. This approach is validated through the API conductivity experiments that mimic the behavior of a fracture at reservoir conditions. The positive results obtained from this research allow suggesting that the technique will have great potential if deployed in the actual field operations.
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Mironovs, Viktors, Vadims Sokolovs, Vjačeslavs Zemchenkovs, Jekaterina Kuzmina, Viktorija Stankevica, and Vjaceslavs Lapkovskis. "Investigation of a Shock Freezing Concept with Additional Electromagnetic Field Exposure." In Materials Engineering and Modern Manufacturing 2023. Switzerland: Trans Tech Publications Ltd, 2023. http://dx.doi.org/10.4028/p-dlyu4l.
Abstract:
Widely used to preserve foods for long-term preservation, freezing is a standard method of preserving food goods. This technique is highly energy-intensive and time-consuming. Utilising shock freezing techniques helps to accelerate the process. The current paper analyses information regarding the technology and application of shock-freezing technologies, including those utilising electromagnetic and electric fields. The results of experiments conducted using a refrigerator equipped with an electromagnetic system are reported. In order to achieve the research objectives, coils were installed in the refrigerator to induce an alternating electromagnetic field with an electromagnetic induction value of up to 0.6 mT. Preliminary experiments were carried out using sodium chloride solutions with various concentrations found in perspective frozen food products.
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Das, Debasis P., Parimal A. Patil, Pankaj K. Tiwari, Renato J. Leite, and Raj Deo Tewari. "Reservoir Characterization for Uncertainty Analysis and Its Impact on CO2 Injection and Sequestration in a Depleted Offshore Carbonate Gas Field." In SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205706-ms.
Abstract:
Abstract The emerging global climate change policies have necessitated the strategic need for prudent management of produced contaminants and, with cold flaring being no more the best option, Carbon Capture Utilization & Storage (CCUS) technology provides opportunity for development of high CO2 contaminant fields. A typical CO2 sequestration project comprises capturing CO2 by separating from produced hydrocarbons followed by injection of CO2 into deep geological formations for long term storage. While injection ofCO2 may continue over tens of years, the long-term containment needs to be ascertained for thousands of years. Several geological and geophysical factors along with the existingwells need to be evaluated to assess the potential risks for CO2 leakage that maychallenge the long-term containment. This study considers a depleted carbonate field located offshore Sarawak as a possible long-term CO2 storage site. Elements that may lead to possible leakage of CO2over time are the existing faults or fractures, development of new fractures/faults during injection, caprock failure due to pressures exceeding fracture pressure during/after injection and possible leakage through existing wells. The risk assessment process includes identification and mapping of faults and fracture networks, mapping of seals, evaluation of seismic anomalies and gas while drilling records, pore-pressure analysis, laboratory experiments for analyzing changes in geomechanical & geochemical rock properties and well integrity of existing wells. All these parameters are cross correlated, and qualitative risk categorization is carried out to determine the robustness of the reservoir for long term CO2 storage. The evaluation of available data indicates less frequent faulting occur only towards the flank with no seismic anomalies associated with them. Some seismic anomalies are observed at shallower levels, however their impact on the reservoir and overburden integrity is assessed to be minimum. There are four shale dominated formations mapped in the overburden section, which will act as potential seals. Estimated fracture pressures for the potential seals ranges between 6200-9280 psia for the deepest seal to 2910-4290 psia for the shallowest. Therefore,it is interpreted that if the post injection reservoir pressure is kept below the initial reservoir pressure of 4480 psia, it would not hold any threat to the caprock integrity.Leakage rate riskalong the existing wells was determined based on well log data. Well integrity check of legacywells helped identify two abandoned wells for rigorous remediation to restore their integrity. The subsurface risk analysis is critical to ascertain the long-term containment of injectedCO2. The integrated subsurface characterization and well integrity analysis approach adopted in this work can be applied to any other field/reservoir to validate its robustness for long-term CO2 injection and storage.
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Gladysheva, Ol'ga, Oksana Artyuhova, and Vera Svirina. "Crop rotations with clover and their productivity." In Multifunctional adaptive fodder production23 (71). ru: Federal Williams Research Center of Forage Production and Agroecology, 2020. http://dx.doi.org/10.33814/mak-2020-23-71-38-42.
Abstract:
The results of long-term research in experiments with crop rotations with different clover saturation are presented. It is shown that the cluster has a positive effect on the main indicators of vegetation of dark-gray forest soil. The introduction of two fields of perennial grasses into the six-field crop rotation significantly increases both the humus reserves and increases the productivity of arable land by 1.5–2 times compared to the crop rotation with a field of pure steam.
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Porlles, J. W., O. S. Tomomewo, S. A. Afari, E. Gyimah, A. Laalam, and O. Bakelli. "An Experimental Study of the Effect of Long-Term Time-Dependent Proppant Behavior Under HP-HT Reservoir Conditions." In SPE Annual Technical Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/215120-ms.
Abstract:
Abstract The long-term sustainability of fracture conductivity in a geothermal system using proppant will be affected by crushing pressure and geothermal fluids. Previous experiments have shown that for short-term periods, field testing results have indicated some performance improvements and a few experiments for long-term periods have shown that different types of proppants and the crushing test results suggest probable geomechanical degradation of the proppants under the test conditions. So, some proppants, such as ceramics and kryptospheres, showed a significant degree of mechanical strength degradation after exposure to high temperatures and geothermal water formation. In addition, the crushing test does not replicate downhole conditions because the crush test compares the conductivity test and downhole conditions. So, all types of proppants do not crush in the same manner. Sand-based proppants tend to shatter, ceramics tend to cleave, and resin-coated proppant deform as the internal substrate breaks. Moreover, according to the literature review, the EGS projects have used proppants such as quartz sand, ceramic LT, and ceramic HSP. However, in recent years, new types of proppants have been designed to face these challenging conditions. For that reason, supplementary testing is required to comprehensively understand the long-term behavior of the proppants in geothermal reservoirs with low permeability, which we want to use proppants. This investigation analyzes the long-term proppant behavior under high-temperature reservoir conditions and shows that some types of proppants can improve fracture conductivity and support long-term performance in harsh aqueous environments with many thermal cycles on fields such as Utah FORGE or other locations with similar characteristics. So, proppants should work for long-term conductivity and thermal pressurization cycles, between 15000 to 500°F and 5000 to 15000 Psi, respectively. This study presents the results of experimental investigations of crushing tests for different proppants at 9000, 12000, and 15000 psi and the development of a numerical model for hydraulic fracturing design to compare how it affects the fracture permeability with a permanent fracture permeability and variable fracture permeability. Also, it is developed water analyzed to compare the chemical properties before and after combining the proppants with water formation at 260 oC after two weeks. The study focuses on evaluating the permeability drop of the artificially generated fracture throughout its lifetime. The artificial fracture permeability is affected by high reservoir temperature, lithostatic pressure, and chemical components of the water formation. According to previous studies, closure stress and geothermal fluids affect proppants reducing the fracture conductivity for long-term sustainability; instead of keeping the area generated and the high permeability in the artificial fractures. Moreover, the fracture permeability is diminished, and the fracture conductivity and width are reduced, affecting the flow rate and heat extraction. So, different kinds of proppants were evaluated under different closure pressure with a crushing test to determine the percentage of destruction after two weeks under high temperatures (260 °C); new proppants have a high crush resistance and withstand stress cycling to ensure that fracture conductivity and connectivity are sustained long-term to optimize production. Hence, a numerical simulation model was developed to compare economically different scenarios of fracture permeability (permanent and variable), fracture length, fracture width, flow rate, and reservoir temperature to determine the feasibility of developing an EGS project stimulated by HF.
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Pa´kozdi, Csaba, and Mateusz Graczyk. "Validation of an SPH Sloshing Simulation by Experiments." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79792.
Abstract:
Sloshing is a violent fluid motion and is of current interest for many branches of the industry, among them gas shipping. Numerical methods are an important tool for analyzing sloshing. Among them, methods based on the smooth particle hydrodynamics (SPH) are particularly promising for analyzing violent fluid impacts. Previous work shows a good agreement in terms of free surface elevation between SPH simulation and experiments. An extensive comparison in terms of pressure in the tank is missing. This is due to the fact that availability of reliable and accurate pressure measurements is limited. Therefore sloshing experiments in a two-dimensional tank are performed. A regular one-degree-of-freedom motion with small amplitude is imposed for various frequencies around fluid natural frequency and three filling levels in range 17–40% of the tank length. By means of pressure sensors mounted on the vertical tank wall the pressure is measured for a non-impact type fluid motion. Free surface elevation is measured by wave probes and a high speed video recording is taken. An in-house SPH code is presented in detail. Standard SPH formulation is modified with the focus on implementation of the Verlet time scheme. The Verlet time integration scheme makes it possible to perform long time sloshing simulations due to its good momentum and energy conservation properties. A diffuse term coefficient is applied in the continuity equation. Investigated sloshing cases are without violent fluid impacts. Using artificial mass diffusion term in SPH simulations is expected not to significantly influence the pressure field. The paper shows that applying this technique with carefully chosen coefficient does not lead to any nonphysical phenomena in the SPH simulation for such a sensitive phenomenon as sloshing. By comparing the SPH simulations to the quasi-analytical multimodal method and experiments the code and diffuse term coefficient are validated.
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Bacon, Diana H., Michael I. Ojovan, B. Peter McGrail, Natalie V. Ojovan, and Irene V. Startsceva. "Vitrified Waste Corrosion Rates From Field Experiment and Reactive Transport Modeling." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4509.
Abstract:
The Hanford Site in southeastern Washington State has been used extensively by the U.S. Department of Energy (DOE) to produce nuclear materials for the U.S. strategic defense arsenal. A large inventory of radioactive and mixed waste has accumulated in 177 buried single- and double-shell tanks. Liquid waste recovered from the tanks will be pre-treated to separate the low activity fraction from the high-level and transuranic wastes. The low-activity waste (LAW) will be immobilized in glass and placed in a near-surface disposal system on the Hanford Site. Vitrifying the LAW will generate over 160,000 m3 of glass. Before the immobilized low-activity waste (ILAW) can be disposed, DOE must approve a performance assessment (PA), which is a document that describes the long-term impacts of the disposal facility on public health and environmental resources. A sound scientific basis for determining the long-term release rates of radionuclides from LAW glasses must be developed if the PA is to be accepted by regulators and stakeholders. To conduct this calculation, Pacific Northwest National Laboratory (PNNL) used a methodology in which the waste form release rate was calculated by modeling the basic physical and chemical processes that are known to control dissolution behavior using a reactive transport code, STORM [1]. This methodology was used instead of empirical extrapolations from laboratory “leaching” experiments commonly used in other PA or in the phenomenological approach of SIA “Radon” [2]. This methodology is preferred because the dissolution rate, and hence radionuclide release rate, from silicate glasses is not a static variable—a constant that can be derived independently of other variables in the system. Glass dissolution rate is a function of three variables (neglecting glass composition itself): temperature, pH, and composition of the fluid contacting the glass. SIA Radon has been running a field experiment for over 12 years to evaluate the behavior of a high sodium glass buried in a loamy soil. The radioactive waste glass (K-26) made from actual intermediate-level waste from the Kursk (RBMK) reactor was manufactured and placed in a shallow trench. The waste stream was 86 mass% NaNO3, very similar to the salt content expected for Hanford LAW. The final glass composition had a Na2O content of roughly 16 mass%, making it very relevant to the glass formulations being considered at Hanford. A joint US DOE-SIA Radon project was devised to validate the modeling approach used for the ILAW PA by modeling glass corrosion in the subsurface experimental facility [3]. This paper gives an estimate of glass corrosion and ion exchange rates for K-26 waste glass based on field measurements.
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Lemmens, Karel, Marc Aertsens, Véra Pirlet, Hélène Serra, Elie Valcke, Pierre De Cannière, and Pierre Van Iseghem. "Measurement of Glass Corrosion in Boom Clay Disposal Conditions." In ASME 2001 8th International Conference on Radioactive Waste Management and Environmental Remediation. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/icem2001-1286.
Abstract:
Abstract To estimate the life-time of vitrified high level waste (HLW-glass) in geological disposal conditions in Boom Clay, the dissolution behaviour of waste glass has been studied in experiments in surface laboratories and in the HADES underground research facility of SCK•CEN since the 1980’s. The programme consists mainly of dissolution tests. The purpose of these tests is to understand the basic glass dissolution mechanisms, and to demonstrate realistic long-term dissolution rates. The main experimental variables are glass composition, environmental materials, temperature, and test duration. The studied glasses are the COGEMA glass R7T7, and the PAMELA glasses with SM539, SM527 and SM513 glass frit. The environmental materials comprise Boom Clay, metallic corrosion products and engineered barrier materials. Dissolution tests have been performed at temperatures from 40 to 190°C, for test durations from days to several years. The tests are performed with inactive glasses, which can be doped with radionuclides of interest. Because of the importance of silica sorption by the environmental materials, the dissolution test programme was extended with silica diffusion- and sorption tests in Boom Clay and FoCa clay. The interpretation of the experimental results is supported by geochemical and kinetic modeling. In the area of kinetic modeling, both analytical and Monte Carlo codes are applied. The dissolution tests have demonstrated that, although the presence of Boom Clay initially increases the glass dissolution rate, the long-term dissolution rate decreases for diluted clay / clay water slurries. This decrease has not yet been demonstrated for the R7T7 glass in compact Boom Clay, but is expected to occur here also on the long term. The dissolution rate decreases faster after sufficient addition of glass powder to the medium. This was tested in experiments with the R7T7 glass at relatively high clay concentration (2000 g of humid Boom Clay per liter clay water, this is about half the solid/liquid ratio of compact Boom Clay), at 40 and 90°C. Linear interpolation of the long-term mass losses resulted in dissolution rates of ∼ 0.01 g.m−2.day−1. The statistical uncertainties on the dissolution test results did not allow to demonstrate smaller rates. The minimum statistically significant dissolution rate depends on the test conditions. Therefore, the present SCK•CEN programme includes dissolution tests at long-term near-field conditions (this is at 30°C, with compact Boom Clay and FoCa clay), which are considered more representee for the long-term situation. In view of the uncertainties on the experimental long-term dissolution rates and on the long-term dissolution mechanisms, rates smaller than 0.01 g.m−2.day1 (about 1 μ/year) should not be used as best estimate in the present performance assessment studies for disposal in Boom Clay. A constant dissolution rate of 0.01 g.m−2.day−1 would correspond to a dissolution time for a R7T7 glass package of approximately 150 000 years. The minimum dissolution time is of the order of 104 years.
Reports on the topic "Long-term field experiments":
1
Thompson and Lawson. L51959 Cathodic Protection Requirements for Mitigation Corrosion on Buried Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2002. http://dx.doi.org/10.55274/r0011277.
Abstract:
As pipelines age, the need for predictive capability and comprehensive models for cathodic protection and corrosion mitigation is becoming significantly more critical. It is imperative that such models be developed to insure future pipeline integrity and risk management that is both economically feasible and utilizes best-practice engineering. Present cathodic protection (CP) models are based on a simplified mechanism of cathodic protection that does not explain certain basic field observations for operating underground pipelines. In addition, the lack of a comprehensive mechanism for cathodic protection of steel in soil environments has prevented industry from developing predictive models for (1) establishing long-term cathodic protection current requirements as a function of pipeline conditions and (2) quantifying the magnitude of corrosion mitigation for a specific level of cathodic polarization. In this study, long-term laboratory experiments were used to define and quantify an environmental polarization effect. The environmental polarization term was capable of explaining most of the field observations concerning current requirements and depolarization. Potentiodynamic polarization tests were utilized to quantify the effects of environmental polarization.
2
Birkemeier, William, Kent Hathaway, Ravi Sinha, Kossi Edoh, Awatif Amin, and Hermant Pendharkar. Long-Term Archive of the DUCK94 Nearshore Field Experiment Data. Fort Belvoir, VA: Defense Technical Information Center, September 2000. http://dx.doi.org/10.21236/ada609935.
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Birkemeier, William, Kent Hathaway, Ravi Sinha, Kossi Edoh, Awatif Amin, and Krishna Kulkarni. Long-term Archive of the DUCK94 Nearshore Field Experiment Data. Fort Belvoir, VA: Defense Technical Information Center, September 1999. http://dx.doi.org/10.21236/ada630859.
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Birkemeier, William, Kent Hathaway, and Ravi Sinha. Long-term Archive of the DUCK94 Nearshore Field Experiment Data. Fort Belvoir, VA: Defense Technical Information Center, August 2001. http://dx.doi.org/10.21236/ada626224.
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Bailey, David M., Stuart D. Foltz, and Myer J. Rosenfield. Long Term Field Test Results of Experimental EPDM and PUF Roofing. Fort Belvoir, VA: Defense Technical Information Center, April 1990. http://dx.doi.org/10.21236/ada226197.
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Dasberg, Shmuel, Jan W. Hopmans, Larry J. Schwankl, and Dani Or. Drip Irrigation Management by TDR Monitoring of Soil Water and Solute Distribution. United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568095.bard.
Abstract:
Drip irrigation has the potential of high water use efficiency, but actual water measurement is difficult because of the limited wetted volume. Two long-term experiments in orchards in Israel and in California and several field crop studies supported by this project have demonstrated the feasibility of precise monitoring of soil water distribution for drip irrigation in spite of the limited soil wetting. Time Domain Reflectometry (TDR) enables in situ measurement of soil water content of well defined small volumes. Several approaches were tried in monitoring the soil water balance in the field during drip irrigation. These also facilitated the estimation of water uptake: 1. The use of multilevel moisture probe TDR system. This approach proved to be of limited value because of the extremely small diameter of measurement. 2. The placement of 20 cm long TDR probes at predetermined distances from the drippers in citrus orchards. 3. Heavy instrumentation with neutron scattering access tubes and tensiometers of a single drip irrigated almond tree. 4. High resolution spatial and temporal measurements (0.1m x 0.1m grid) of water content by TDR in corn irrigated by surface and subsurface drip. The latter approach was accompanied by parametric modelling of water uptake intensity patterns by corn roots and superimposed with analytical solutions for water flow from point and line sources. All this lead to general and physically based suggestions for the placement of soil water sensors for scheduling drip irrigation.
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Buchler, M., H. G. Schoneich, and F. Stalder. DRS04BSS Criteria to Assess the Alternating Current Corrosion Risk of Cathodically Protected Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2004. http://dx.doi.org/10.55274/r0011818.
Abstract:
This paper addresses the assessment of the corrosion risk of a pipeline due to alternating currents. The state of the art technique is the use of coupons, which simulate a coating fault and which allow to measure the ac-current density and also to evaluate corrosion products and pits. Recently, different criteria to assess the corrosion risk have been proposed that are based on the ratio between ac- and dc-current density or the instantaneous off-potential (high-speed off-potential measurement) measured on a coupon. Furthermore, the charge needed to oxidize corrosion products (under alkaline conditions) on a corroded steel surface indicates the level of metal loss. These criteria are discussed on the basis of field experience from coupons and from alternating current-corrosion pits on high voltage interfered pipelines. Results from long term laboratory corrosion measurements under constant AC and DC load are presented which indicate that not only a reduction of pipe/ground AC potential but also a careful adjustment of cathodic protection level helps to minimize a.c. corrosion rates. Based on the results from cyclic potentiodynamic experiments under alkaline conditions, a basic model explaining AC corrosion on cathodically protected pipelines has been developed.
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Matt, Nyman. Evaluation of Students’ Response to Field Trips to HJ Andrews Experimental Forest. Oregon State University, September 2023. http://dx.doi.org/10.5399/osu/1162.
Abstract:
The Andrews Forest Long-Term Ecological Research (LTER) site has a long-term partnership with the University of Oregon Environmental Leadership Program (ELP), providing service-learning opportunities for undergraduate students to facilitate field trips for middle school students to the Andrews LTER site. Undergraduate students develop field trip lessons based on Andrews Forest research and creative inquiry with support of Schoolyard LTER coordinator and Andrews LTER scientist Schulze. In Middle school students hiking in the Andrews LTER 2023, six classes and 156 students total engaged in day-long field trips at the Andrews LTER site that involved forest ecology and tree identification, time to reflect on and connect with the iconic old-growth ecosystems, and discussions about environmental stewardship ideas that the students could implement both at the Andrews LTER site and in their homes. The students came from three different schools, two of them rural schools with low socio-economic status in the Lane County Educational Service District and the other a Montessori school in the Eugene area. This report shares the results from an evaluation project led by Dr. Matt Nyman and Dr. Kari O’Connell that assessed the impact of the field trips on the middle school students. The evaluation was designed to also support the middle school students’ own reflection and learning at the same time as gathering data about the impact of the experience.
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Burdman, S., E. Welbaum, R. Walcott, and B. Zhao. erial fruit blotch, elucidating the mechanisms of fruit infection by Acidovorax citrulli. Israel: United States-Israel Binational Agricultural Research and Development Fund, 2020. http://dx.doi.org/10.32747/2020.8134162.bard.
Abstract:
Bacterial fruit blotch (BFB) of cucurbits is caused by the Gram-negative bacterium Acidovorax citrulli. BFB affects cucurbit production worldwide, and mainly watermelon and melon. Most A. citrulli strains are divided into two genetically differentiated groups: while group I strains have been mainly associated with melon and other non-watermelon cucurbits, group II strains are more aggressive on watermelon. Like many Gram-negative plant-pathogenic bacteria, A. citrulli relies on a functional type III secretion system (T3SS) for pathogenicity. The T3SS is responsible for direct secretion of bacterial protein effectors to the host cell. Type III-secreted effectors (T3Es) contribute to virulence through manipulation of the host cell metabolism and suppression of plant defense. Our previous collaboration showed that group I and II strains significantly differ in their T3E arsenal (Eckshtain-Levi et al., Phytopathology 2014, 104:1152-1162). Using comparative genomics, we also showed that group I and II strains of A. citrulli have substantial differences in their genome content (Eckshtain-Levi et al., Front. Microbiol. 2016, 7:430). Our long-term goals are to identify the genetic determinants that contribute to virulence and host preferential association of the two major groups of A. citrulli, and to exploit these insights to develop effective BFB management strategies. We hypothesize that differences in the arsenal of T3Es, are greatly responsible for the differences in host preferential association between strains belonging to the two groups. The specific objectives of this project were: (1) to investigate the susceptibility of cucurbit species to group I and II strains under field conditions; (2) to assess the contribution of T3Es and other virulence factors to A. citrulli virulence and host preference; and (3) to characterize the mechanisms of action of selected T3Es of A. citrulli. In the frame of objective 1, we carried out three field experiments involving inoculation of several cucurbit crops (watermelon, melon, pumpkin and squash) with group I and II strains. Findings from these experiments confirmed that A. citrulli strains exhibit a preference for watermelon and melon. Moreover, we demonstrated, for the first time under field conditions, host-preferential association of group I and II strains to melon and watermelon, respectively. While host-preferential association was observed in leaves and in fruit tissues, it was more pronounced in the latter. In this part of the project we also developed a duplex PCR assay to differentiate between group I and II strains. In the frame of objective 2, we employed a multifaceted approach combining bioinformatics and experimental methods to elucidate the T3E arsenal of A. citrulli. These experiments led to discovery that A. citrulli strains possess large arsenals with more than 60 T3E genes. Remarkably, we found that ~15% of the T3E genes are group-specific. Advances were achieved on the contribution of selected T3E genes and other virulence determinants to the ability of A. citrulli to colonize the fruit and other tissues of melon and watermelon. Last, in the frame of objective 3, we advanced our understanding on the mode of action of few key T3Es of A. citrulli. We also optimized a virus-induced gene silencing (VIGS) system for functional genomics in melon and watermelon. This system will allow us to test melon and watermelon genes that may have defense or susceptibility roles related to BFB disease. Overall, this collaboration substantially enriched our knowledge on basic aspects of BFB disease. We believe that the fruits of this collaboration will greatly contribute to our ultimate goal, which is generation of durable resistance of melon and watermelon to A. citrulli.
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Banin, Amos, Joseph Stucki, and Joel Kostka. Redox Processes in Soils Irrigated with Reclaimed Sewage Effluents: Field Cycles and Basic Mechanism. United States Department of Agriculture, July 2004. http://dx.doi.org/10.32747/2004.7695870.bard.
Abstract:
The overall objectives of the project were: (a) To measure and study in situ the effect of irrigation with reclaimed sewage effluents on redox processes and related chemical dynamics in soil profiles of agricultural fields. (b) To study under controlled conditions the kinetics and equilibrium states of selected processes that affect redox conditions in field soils or that are effected by them. Specifically, these include the effects on heavy metals sorption and desorption, and the effect on pesticide degradation. On the basis of the initial results from the field study, increased effort was devoted to clarifying and quantifying the effects of plants and water regime on the soil's redox potential while the study of heavy metals sorption was limited. The use of reclaimed sewage effluents as agricultural irrigation water is increasing at a significant rate. The relatively high levels of suspended and, especially, dissolved organic matter and nitrogen in effluents may affect the redox regime in field soils irrigated with them. In turn, the changes in redox regime may affect, among other parameters, the organic matter and nitrogen dynamics of the root zone and trace organic decomposition processes. Detailed data of the redox potential regime in field plots is lacking, and the detailed mechanisms of its control are obscure and not quantified. The study established the feasibility of long-term, non-disturbing monitoring of redox potential regime in field soils. This may enable to manage soil redox under conditions of continued inputs of wastewater. The importance of controlling the degree of wastewater treatment, particularly of adding ultrafiltration steps and/or tertiary treatment, may be assessed based on these and similar results. Low redox potential was measured in a field site (Site A, KibutzGivat Brenner), that has been irrigated with effluents for 30 years and was used for 15 years for continuous commercial sod production. A permanently reduced horizon (Time weighted averaged pe= 0.33±3.0) was found in this site at the 15 cm depth throughout the measurement period of 10 months. A drastic cultivation intervention, involving prolonged drying and deep plowing operations may be required to reclaim such soils. Site B, characterized by a loamy texture, irrigated with tap water for about 20 years was oxidized (Time weighted average pe=8.1±1.0) throughout the measurement period. Iron in the solid phases of the Givat Brenner soils is chemically-reduced by irrigation. Reduced Fe in these soils causes a change in reactivity toward the pesticide oxamyl, which has been determined to be both cytotoxic and genotoxic to mammalian cells. Reaction of oxamyl with reduced-Fe clay minerals dramatically decreases its cytotoxicity and genotoxicity to mammalian cells. Some other pesticides are affected in the same manner, whereas others are affected in the opposite direction (become more cyto- and genotoxic). Iron-reducing bacteria (FeRB) are abundant in the Givat Brenner soils. FeRB are capable of coupling the oxidation of small molecular weight carbon compounds (fermentation products) to the respiration of iron under anoxic conditions, such as those that occur under flooded soil conditions. FeRB from these soils utilize a variety of Fe forms, including Fe-containing clay minerals, as the sole electron acceptor. Daily cycles of the soil redox potential were discovered and documented in controlled-conditions lysimeter experiments. In the oxic range (pe=12-8) soil redox potential cycling is attributed to the effect of the daily temperature cycle on the equilibrium constant of the oxygenation reaction of H⁺ to form H₂O, and is observed under both effluent and freshwater irrigation. The presence of plants affects considerably the redox potential regime of soils. Redox potential cycling coupled to the irrigation cycles is observed when the soil becomes anoxic and the redox potential is controlled by the Fe(III)/Fe(II) redox couple. This is particularly seen when plants are grown. Re-oxidation of the soil after soil drying at the end of an irrigation cycle is affected to some degree by the water quality. Surprisingly, the results suggest that under certain conditions recovery is less pronounced in the freshwater irrigated soils.